It is a traditional practice and an act of piety to have your home blessed between Epiphany and before the feast of the Presentation, the true end of the Christmastide period.
Chalk previously blessed is used to inscribe the formula:
20 + C + M + B + 19
The 20 and 19 at either end clearly relate to the year in question with the C, M and B referring to Caspar, Melchior and Balthazar – the three Magi.
To arrange for your house to be blessed, be contact a priest at the Shrine.